my personal statement for uni is looking quite blank here bc of covid, would it be advisable to put it on my personal statement?
That depends entirely on your target audience. Generally, they’d be looking for achievements though. Saying just “method of loci” is a bit like saying “hammer and nail.” That’s really just a “tool” you know… and more than likely not even a tool that they’d be familiar with.
It be something else if you could say “Participated in the Hong Kong Memory Open” or you got yourself onto the Pi world ranking list (https://www.pi-world-ranking-list.com), so that the whole thing is somewhat more tangible to the reader.